Phosphorus-containing gasoline motor fuels



United States Patent Oifice 3,095,285 Patented June 25, 1963 15' Claims- (CI. 4458) This invention relates to motor fuels containing certain novel addition agents. More particularly, the invention relates to gasoline motor fuels containing new addition products of olefin oxides and dialkyl orthophosphoric acids.

It has long been recognized that high compression ratios are desirable in gasoline engines for greater fuel economy and greater engine efiiciency. In striving for these objectives, many automobile manufacturers have already increased the compression ratios of their spark ignition engines to 8.5:1, 9:1, or even higher. The present trend of the automotive industry indicates that within the foreseeable future substantially all engines will be operating at least at these and perhaps at higher compression ratios.

In order to obtain smooth engine operation at these high compression ratios it has been necessary to employ fuels having high octane values. To obtain the required high octane values, most fuels require addition of an antiknock agent such as tetraethyl lead. Although the addition of tetraethyl lead to gasoline improves its octane number, the resulting fuel exhibits certain disadvantages owing to the presence of the lead. One of the several objections to the use of leaded gasolines arises from the tendency of such fuels to form lead decomposition products on combustion. These decomposition products are deposited within engine combustion chambers, for example on piston and cylinder heads, and on spark plug electrodes and insulators. The decomposition products normally comprise mostly oxides, sulfates, bromides and chlorides of lead. As the quantity of lead-containing engine deposits builds up, engine octane number requirements gradually increase until some equilibrium octane number requirement is reached. For example, the equilibrium octane number requirement of an engine which has been in operation for 100 or more hours may be 10 to numbers higher than the octane number requirement of the same engine at the start of its operation. In this manner, the lead deposits reduce engine efficiency and partially offset the benefits obtained with the high compression ratios.

In an attempt to reduce the deposits, various scavenging agents have been added to the fuels. These agents function as lead scavengers by promoting formation of lead decomposition products that are more volatile and thus less likely to be deposited within said engines. Volatile alkyl halides such as ethylene dibromide and/or ethylene dichloride are examples of lead scavengers that have been used in gasoline in conjunction with tctraethyl lead. These alkyl halides assist in the conversion of tetraethyl lead to the corresponding lead halides during gasoline combustion. The lead halides are more volatile than lead oxides and the like and thus exhibit reduced deposit-forming tendencies.

However, the use of volatile alkyl halides in leaded gasolines has not completely overcome the problem of deposition in engines of tetraethyl lead decomposition products. Thus, notwithstanding the use of such volatile alkyl halides, significant, detrimental amounts of lead deposits are found and deposited Within the combustion chambers of internal combustion engines.

detrimental efiect of engine As indicated briefly above, the lead-containing decomposition products deposited within the combustion chambers of high compression, internal combustion engines adversely affect the ignition characteristics of such engines. These deposits tend to promote preignition of the fuel during the compression thereof. The adverse effect caused by these deposits is frequently evidenced by engine knocking. The knocking thus encountered is that associated with preignition and combustion during compression of the fuel in the combustion chambers of internal combustion engines of the spark ignition, reciprocating type, and this knocking is not to be confused with knocking caused by explosive autoignition of unburned fuel-air mixture prior to traversal thereof by the normal spark plug flame.

As a matter entirely apart from the problem of preignition due to engine deposits, it has also been found that when an internal combustion engine is operated under cool, humid atmospheric conditions, using a gasoline fuel having a relatively low 50 percent ASTM distillation point, i.e., below about 235 F., excessive engine stalling is apt to be encountered at idling speeds during the warm-up period, especially Where engine idling occurs following a period of light load operation. Engine stalling under such conditions has been attributed to the partial or complete blocking of the narrow air passage that exists between the carburetor throat and the carburetor throttle valve during engine idling, by ice particles and/or solid hydrocarbon hydrates that deposit upon and adhere to the metal surfaces of the carburetor parts. Such icing of carburetor parts occurs as a result of the condensation of moisture from the air drawn into the carburetor and as a result of the solidification of such condensed moisture. The aforesaid condensation and solidification of moisture are caused by the refrigerating effect of rapidly evaporating gasoline. Accordingly, excessive engine stalling due to carburetor icing occurs as a practical matter only in the instance of gasolines containing a large proportion of relatively highly volatile components. In practice, a high degree of engine stalling due to carburetor icing has been found to occur, under cool, humid atmospheric conditions, in connection with gasolincs having a 50 percent ASTM distillation point below about 235 F.

Excessive engine stalling is, of course, a source of annoyance owing to the resulting increased fuel consumption, battery wear and inconvenience of frequent restarting. It is therefore important that the inherent engine stalling characteristics of gasoline fuels be reduced substantially, where the 50 percent ASTM distillation point of such gasoline fuels is sufiicicntly low to cause a problem in this respect.

We have found that the use of small amounts, for example 01303 to 0.5, of the substantially neutral addition products of C to C olefin oxides and dialltyl acid orthophosphates whose alkyl groups contain 5 to 8 carbon atoms will improve various properties of gasoline motor fuel compositions. Thus, these addition products Will reduce the preignition tendencies of gasoline motor fuel compositions that contain tetraethyl lead in an amount normally tending to cause preignition in the combustion chambers of spark ignition, reciprocating engines; likewise, the same addition products will tend to reduce the engine stalling tendencies of gasoline compositions having a 50 percent ASTM distillation point below about 235 F. The present invention includes gasoline fuel compositions containing addition products of the class described.

When used in effective proportions in leaded gasolincs the addition products disclosed herein tend to reduce the over-all quantity of lead deposits, and they may also function to reduce the capacity of any remaining lead deposits to preignite gasoline-air mixtures. When used in antistalling proportions, it might appear that by virtue of their polarity the herein-disclosed addition agents tend to orient themselves upon the metal surfaces of the throttle valve and other critical carburetor parts contacted by the gasoline composition, thus forming a moisture-displacing, residual coating on said carburetor parts, which coating tends to prevent the adherence to said metal surfaces of accumulations of ice of magnitudes sutficient to block the narrow air passages that exist in carburetors at engine idling conditions. It is also considered that the molecules of the herein-disclosed addition agents may orient themselves about small individual water or ice particles, thus tending to prevent the formation of macrocrystals of ice of a size sufiicient to block carburetor air passages at engine idling conditions. Such explanations, however, are somewhat negatived by the fact that many oil-soluble, polar materials have no antistalling properties whatever.

When the herein disclosed addition agents are utilized in gasoline compositions that contain a small amount of a light lubricating oil, it is thought that the herein disclosed addition products, by virtue of their afiinity for the lubricating oil, tend to attract the oil to the same critical carburetor surfaces referred to above, while simultaneously increasing the spreading and metal wetting characteristics of the oil, thus promoting the formation of an adherent oil film on the metal surfaces of the carburetor parts. The oil film thus appears to function similarly as the addition products themselves, but the superior metal wetting properties imparted to the oil by the additive are believed to enable the oil to displace moisture from the metal carburetor surfaces that it would not thoroughly displace alone.

In accordance with this invention, the addition products of the class described herein are prepared by reacting an olefin oxide that contains 2 to 4 carbon atoms per molecule with a dialkyl ester of orthophosphoric acid whose alkyl groups contain 5 to 8 carbon atoms, in proportions such as to provide a substantially neutral addition product, that is, one having a pH of about 5 to 6.8. Usually several mols of olefin oxide per mol of dialkyl acid orthophosphate will be required to produce a substantially neutral product. The actual number of mols required can vary somewhat with the identity of the olefin oxide and of the dialkyl phosphate. The substantially neutral products can be conveniently obtained by addition of olefin oxide in small increments to the dialkyl acid orthophosphate, under ordinary atmospheric conditions of temperature and pressure, and determining the pH of the reaction mixture following the addition of each such increment. The reaction is regarded as complete for the purposes of this invention when the reaction mixture possesses a pH of about 5 to 6.8. The neutralization reaction described is normally exothermic and takes place spontaneously at room temperature to the degree indicated. Although additional olefin oxide can be added to the reaction mixture and reacted therewith under increased temperature and pressure, after a substantially neutral addition product has been obtained at ambient conditions, the resulting product will be relatively less effective, on a weight basis, for anti-preignition purposes. Accordingly, we prefer to add only the amount of olefin oxide that is necessary to obtain a pH within the range indicated.

The dialkyl acid orthophosphates suitable for use in the foregoing reaction can be prepared in any convenient manner. For example, they can be prepared by reacting a monohydric alcohol containing 5 to 8 carbon atoms with phosphoric anhydride (P in the proportion of 4 mols of alcohol per mol of anhydride. This reaction is exothermic and commences spontaneously at room temperature. However, in order to cause substantially all of the phosphoric anhydride to react, it may be desirable toward the end of the reaction period to raise the temperature of the reaction mixture to a maximum of about 260 F., until all solid phosphoric anhydride disappears.

The use of alcohols containing more than 8 carbon atoms is undesirable, since the addition products derived from phosphate esters of such alcohols tend to promote fuel intake deposits and are less effective inhibitors of prcignition. On the other hand, addition products derived from phosphate esters of alcohols containing less than 5 carbon atoms show significantly reduced oil-solubility.

Specific examples of preferred monohydric alcohols that can be used to obtain dialkyl acid orthophosphates that are useful in preparing the addition products disclosed herein are Z-methylbutyl alcohol, Z-ethylhexyl alcohol and the mixed highly branched chain octyl alcohols known as Oxo-octyl alcohols. Oxo alcohols normally comprise mixtures of isomeric, mostly branched chain,

* primary monohydric alcohols produced by the Oxo synthesis process. The Oxo synthesis process as is wellknown involves the catalytic hydroformylation of monoolefins, such as, for example, hexene and heptene, usually in the form of a mixture of isomers such as can be obtained by nonselective polymerization of the C C or mixed C and C monoolefins present in refinery gases, with a mixture of carbon monoxide and hydrogen, to obtain a mixture of oxygenated products, principally alde hydes, having one more carbon atom per molecule than the original monoolefin. The mixture of oxygenated products is then catalytically hydrogenated to produce Oxo alcohols. Examples of other alcohols that can be used to prepare suitable dialkyl phosphates are n-amyl alcohol, n-hexyl alcohol, 4-methylamyl alcohol, 3-methylbutyl alcohol, n-heptyl alcohol and t-octyl (1,1-dimethylhexyl) alcohol.

Specific examples of preferred dialkyl acid orthophosphates are di-(3-methylbutyl) acid o-phosphate, 3-methylbutyl, Z-ethylhexyl acid o-phosphate, and the di-Oxooctyl acid o-phosphate. Examples of other dialkyl acid o-phosphates that can be used to prepare addition products whose use is included by this invention are di-(2-ethylhexyl) acid o-phosphate, di-n-heptyl acid o-phosphate, dit-octyl o-phosphate, and di-(4-methylamyl) acid o-phosphate.

A specific example of an olefin oxide that is preferred in the preparation of addition products whose use is included by this invention is propylene oxide (1,2-oxypropylene). Examples of other olefin oxides that can be used are ethylene oxide and butylene oxide, either the 1,2 or 2,3 isomer.

The products resulting from the substantial neutralization of a dialkyl acid orthophosphate with an olefin oxide are usually light-colored, slightly viscous, oil-soluble liquids, These addition products will comprise principally alkyloloxyalkylene dialkyl orthophosphates having the generic formula:

where R and R are alkyl groups containing 5 to 8 carbon atoms, where R" and R' are methyl, ethyl or hydrogen groups, the total number of carbon atoms in the R and R' groups being not greater than 2, and n is an average number of at least 2, preferably 2 or 3. Although the class of compounds indicated above is considered to include the principal components of the herein-disclosed reaction products, it will be appreciated that the reaction mixture undoubtedly contains a mixture of products. For example, the reaction mixture can contain products having the formula indicated above where n is 0 to 7 or more. For this reason we prefer to refer to the herein-disclosed addition agents as substantially neutral addition products, rather than as specific chemical compounds.

Specific examples of preferred addition products whose use is included by this invention are the substantially neutral addition products of propylene oxide and di-(3- methylbutyl) acid o-phosphate, B-methylbutyl, Z-ethylhexyl acid o-phosphate and di-tOxo-octyl) acid o-phosphate. Specific components of these addition products are 2-hydroxy-4,7-dioxa-5,8-dimethylnonyl di-(El-methylbutyl) o-phosphate, 2-hydroxy-4,7,10-trioxa-5,8,l l-trimethyldodecyl 3-methylbutyl, 2-ethylhexyl o-phosphate, and 2-hydroxy-4,7-dioxa 5,8 dimethylnonyl di-(Oxooctyl) o-phosphate. Examples of other addition products whose use is included by this invention are the substantially neutral addition products of ethylene oxide, propylene oxide, and for example, 1,2-buty1ene oxide, and di-(Z- ethylhexyl) acid o-phosphate, di-n-heptyl acid o-phosphate, di-t-octyl acid o-phosphate, and di-(dimethylhexyl) acid o-phosphate.

The preparation of a preferred class of addition products is illustrated by the following specific embodiments.

EXAMPLE I Phosphoric anhydride (P in the amount of 17.38 parts by weight was gradually added to 43.08 parts by Weight of isoamyl alcohol, these quantities being equivalent to an approximate mol ratio of about 1 mol of anhydride per 4 mols of alcohols. The reaction proceeded spontaneously and exothermically in the early stages, the rate of addition of phosphoric anhydride being controlled to maintain a maximum reaction temperature of 120 F. When all of the phosphoric anhydride had been added, the temperature of the reaction mixture was raised to a maximum of about 260 F. until all of the phosphoric anhydride went into solution. To the phosphate ester product of the initial reaction there was then added 39.54 parts by weight of propylene oxide. The mol ratio of reactants was about 3 mols of propylene oxide per mol of phosphate ester. This reaction was carried out under reflux with the propylene oxide being added in small increments down the tube of a reflux condenser. The rate of addition of propylene oxide was controlled so as to avoid formation of liquid slugs in the condenser tube. The addition of propylene oxide was commenced under atmospheric conditions of temperature and pressure. The reaction proceeded spontaneously with evolution of heat. Theproduct of the foregoing reactions was a substantially neutral addition product of propylene oxide and di (3-methylbutyl) acid o-phosphate, consisting chiefly of 2 hydroxy 4,7 dioxa-5,8-dirnethylnonyl di-(S-methylbutyl) o-phosphate, and having the following inspections:

Gravity, .API 6.2 Viscosity, SUV, sec., 100 F 91.3 Flash, 0C, "F. 125 Pour, F. 80 Appearance Bright Physical state, room temp. Liquid Color, ASTM Union 1.0 Phosphorus, percent 7.85 Water by distillation, percent by wt., ASTM 995-46 (mod) Trace Neutralization value, ASTM D974-54T, total acid number 0.02 pH value, glass-calornel electrodes 6.4

EXAMPLE 11 Another addition product was prepared as indicated tion product prepared according to this example had the following inspections:

Another addition product was prepared by reacting 30.45 parts by weight of propylene oxide with 69.55 parts by weight of a previously prepared 3-methylbutyl, Z-ethylhexyl acid o-phosphate. These quantities corresponded to a mol ratio of about 4 mols of propylene oxide per mol of phosphate ester. The principal component of the prod not of the foregoing reaction was 2-hydroxy-4,7,l0-trioxa- 5,8,l'l-trimethyldodecyl S-methylbutyl, Z-ethylhexyl 0- phosphate. The addition product prepared according to this example had the following inspections:

Gravity, API 13.6 Viscosity, SUV, sec., F. 86.3 Flash, OC, F Pour, F. 70 Appearance Bright Physical state, room temp Liquid Color, ASTM Union 2.0 Phosphorus, percent 5.76 Water by distillation, precent by wt., ASTM D95-46 (mod) 0.3

Neutralization value, ASTM D974-S4T, total acid number 1.26 pH value, glass-calornel electrodes 6.4

It is understood that the foregoing examples are illustrative only and that other substantially neutral addition products within the scope of this invention can be similarly prepared as above by the substitution of equivalent proportions of other alcohols and/or olefin oxides disclosed herein as suitable for use.

The addition products disclosed herein are useful when used in motor fuels in a wide range of proportions. For example, they are useful when used in amounts of 0.003 to 0.5 percent by weight of the motor'fuel compositions.

The substantially neutral addition products prepared as disclosed herein are excellent inhibitors of preignition caused by lead deposits. These addition agents can be added as such to leaded gasolines having a normal tendency toward preignition, or they can be added in the form of concentrates. Examples of suitable concentrates for the purpose of this invention are kerosene solutions containing 25 percent, respectively, of the addition products prepared in accordance with Examples 'I, II, and HI. Naturally, where the addition agents are employed in the form of concentrates rather than in undiluted form larger proportions of the concentrate will be required in order to obtain effective results. For example, where it is determined that for eliective results 0.036 weight percent of the addition product of Example 11 is desired for use in a gasoline composition containing 3 ml. tetraethyl lead per gallon of 60 API gasoline for elfective results, it will be necessary to incorporate 0.144 weight percent, or four times as much, of a 25 weight percent concentrate of the same addition product, in the same gasoline to obtain the same degree of improvement. If desireithe concentrates in which the addition products of this invention are employed can contain other conventional additive agents designed to improve oneor more properties of the gasoline. For example, the concentrates can contain one or more of the following: upper cylinder lubricants, oxidation inhibitors such as N,N'-di-secbutyl-p-phenylene diamine, 2,4-dimethyl-6-t-butylphenol, and 2,6-di-t-butyl, 4-methylphenol, antistalling and antirust agents such as the cocoamine salt of S-methylbutyl, 2-ethylhexyl acid orthophosphate, metal deactivators such as N,N'-disalicylidene-l,Z-diaminopropane, dyes, and antiknock agents such as tetraethyl lead, and ethylene dihalide scavenging agents such as ethylene dichloride and/or ethylene dibromide.

As previously indicated, when used in gasolines that contain tetraethyl lead in an amount normally tending to cause preignition, the addition agents of this invention are effective, in relatively small proportions, to inhibit preignition. The problem of preignition is important in connection with gasolines of at least about 90 octane (research) that contain at least about 1.5 ml. of lead per gallon, since such gasolines will normally involve a preignition problem when used in high compression engines, e.g., 9:1 compression ratio. The actual quantity of addition agents required for effective results in any particular case will vary principally according to the quantity of tetraethyl lead in the fuel. Since the weight proportions of the addition products of this invention will also vary with the molecular weight of the addition agent and with the specific gravity of the gasoline composition, as well as the lead content of the gasoline, we prefer to express the useful proportions of the herein-described addition agents in terms of the quantity of addition product that is theoretically required to convert the lead in the fuel to lead orthophosphate. Because of the factors indicated above, this is the conventional method used in industry for expressing anti-preignition agent concentrations. The theoretical quantity of preignition agent required to convert the lead in a given fuel composition to lead orthophosphate is referred to as one theory" of that agent. On a theoretical basis 2 mols of the addition agents of this invention are required to completely convert 3 mols of tetraethyl lead to lead orthophosphate.

As a general proposition the addition agents disclosed herein will be elfective in leaded gasolines normally tending to preignite when used in the proportions of about 0.15 to about 1.5 theories. Actually, the addition agents can be used in amounts greater than about 1.5 theories, but when so used no further improvement in anti-preignition characteristics Will be exhibited by the gasoline. The optimum concentration of the addition agents can vary within the range indicated above according to the amount of ethylene dihalide lead scavengers present in the gasoline, larger proportions of the addition agents being desirable with low concentrations of ethylene dihalide, and vice versa. In instances where the tetraethyl lead in the gasoline is employed in the form of commercial mixtures containing about 40 to 50 volume percent ethylene dihalide, effective inhibition of the preignition characteristics of the loaded gasoline will be obtained by the use of about 0.2 to about 0.4 theories of the herein-disclosed addition products, and this constitutes the preferred range of concentrations for the purposes of this invention.

By way of relating concentrations expressed in theories to specific weight proportions of a specific addition agent disclosed herein, it can be noted that 0.15 and 1.5 theories of the addition agent of Example I in a gasoline having an API gravity of 64.3 and containing 1.5 ml. per gallon of tetraethyl lead will correspond, respectively, to .012 and 0.116 percent by weight of the composition of the addition agent. Similarly, 0.15 and 1.5 theories of the addition agent of Example III in the same base gasoline, containing 4.6 ml. of tetnaethyl lead per gallon, will correspond, respectively, to 0.044 and 0.443 percent by weight of the composition of the addition agent. The specific proportions referred to above and elsewhere herein are based on the use of essentially pure tetraethyl lead unless otherwise specified.

The addition products described herein are useful as antistalling agents when incorponated in gasoline compositions whose volatility characteristics are such as to cause a stalling problem in an amount sufficient to reduce the engine stalling characteristics thereof. For example, satisfactory results can be obtained with amounts of at least about 0.003 percent by weight of the composition (9 lbs/1000 bbls. gasoline). In order to obtain fully effective results, it is usually desirable to employ at least about 0.01 percent (30 lbs./ 1000 bbls. gasoline) of the hereindisclosed addition products. Normally, for antistalling purposes the addition products disclosed herein need not be used in proportions greater than about 0.01 percent by Weight of the composition, since no further reduction in the stalling tendencies of the gasoline will normally be obtained by the use of larger amounts. Nevertheless, it will be apparent that where both antistalling and anti-preignition properties are desired, concentrations above 0.01 will be used.

It will be appreciated that the optimum concentration of the herein-disclosed addition products as antistalling agents can vary within the disclosed nange according to the particular gasoline employed, since the problem of engine stalling is a function of the 50- percent ASTM distillation point of the gasoline. Thus, greater concentrations of the additive are normally desirable with decreasing 50 percent ASTM distillation point. The optimum concentration of the herein-disclosed addition products as antistalling agents can also vary somewhat according to the particular engine in which the gasoline is used and according to the severity of the atmospheric conditions encountered. With regard to the last mentioned factor, the problem of engine stalling due to carburetor icing resulting from the refrigeration by evaporating gasoline of moisture condensed from the atmosphere has been observed to be significant at temperatures between about 30 and 60 F., e.g., 35, 40, 45, 50 F., and when the relative humidity is in excess of about 65 percent, e.g., 75, 85, 99 percent. The optimum concentration of the herein-disclosed addition products as antistalling additives should be sufficient to effect a substantial reduction in the stalling tendencies of the fuel at the atmospheric conditions of temperature and humidity which are likely to be encountered in service.

Practically speaking, the problem of engine stalling due to carburetor icing caused by rapid evaporation of gasoline occurs only in connection with gasolines having a 50 percent ASTM distillation point of not greater than about 235 F. Accordingly, this invention relates only to gasolines of this type. While occasional engine stalling may occur as a result of carburetor icing at severe atmospheric conditions of temperature and humidity with gasolines having somewhat higher 50 percent ASTM distillation points, experience has indicated that the problem does not assume major importance except with gasolines of the character indicated. The problem of engine stalling due to carburetor icing is especially severe in connection with gasolines having a 50 percent ASTM distillation point of less than about 220" F. The invention is particularly useful in connection with such gasolines.

The motor fuels to which the addition agents of this invention are added for anti-preignition purposes can comprise any hydrocarbon mixture boiling in the gasoline range that contains lead in an amount sufficient to cause a preignition problem, including commercial grades of motor gasoline and aviation gasoline. Motor gasolines are defined in ASTM D439-52T. Aviation gasolines are defined in ASTM D9l0-52T. The base gasolines to which the addition agents of this invention are added can be straight-run gasolines or gasolines obtained from conventional cracking processes, or mixtures thereof. The gasolines to which the addition agents of this invention are added can also contain components obtained from processes other than cracking, such as alkylation,

isomerization', hydrogenation, polymerization, hydrodesulfurization, hydroforming, platforming, or combinations of two or more of such processes, as well as synthetic gasolines obtained from the FischenTropsch and related processes.

In order to demonstrate the preignition-inhibiting characteristics of the class of addition agents described herein, gasoline compositions in accordance with this invention Were made up by incorporating addition agents prepared in accordance with Examples II and III in separate samples of base gasoline made up of 43.4 percent alkylate gasoline distillate, 21.1 percent catalytically cracked gaso line distillate, 32.5 percent platformed gasoline distillate and 4.3 percent spent butane. This base gasoline had the following inspections:

Gravity, API 64.3 Sulfur (lamp), percent 0.029 Cooper dish gum, mg./100 ml. 5.7 Existent gum, mg./100 ml 2.3 Oxidation stability, min. l440 TEL, mL/gal. 1.9 Knock rating, Octane Number:

Research 98.9 Motor 92.0 Reid vaper pressure, lbs. 7.5

Distillation, F.:

Over point 97 End point 374 143 50% 222 90% 298 activator. The make-up of the foregoing gasoline compositions is summarized in the table below:

Example Example Make-up IV compo- V composition sltion Base gasoline described above, percent by y Weight percent Addition agent of Example III:

Theory 0. Weight percent 0.

The foregoing fuel compositions were tested for improved preignition characteristics in comparison with the uninhibited base gasoline described above by combustion of the various gasoline samples in stationary Cadillac engines having a 10:1 compression ratio. These engines were operated with standard spark advance and standard carburetion, and during the course of the test were lubricated with a commercial, premium lubricating oil, Gulf-pride I-ID Select ZO/ZGW. According to the test procedure followed, the engines were operated on a cycling schedule consisting three minutes at 1500 r.p.m., road load (approximately brake horsepower), tEollowed by a one-minute idle at 450 r.p.m.. At the end of each 24-hour period, preignition and engine noise requirements were determined by bringing each engine to 1100 rpm. and one-inch Hg manifold pressure, then accelerating at 1300 rpm. and observing for abnormal combustion noise. At 1300 r.p.m., throttles were opened to 15 inches Hg manifold pressure and the engines were accelerated to 2000 r.p.rn., and observed for abnormal combustion noise. From this point the engine throttles were gradually opened wide, where they were held for three seconds, while observing for combustion abnormalities. After observing abnormal combustion noise using the test fuel, the noise requirement for each engine was then determined by switching from the test fuel to fuels of higher octane, on a trial and error basis, and observing what octane fuel was required to eliminate com- 'bustion abnormalities. Test results were reported as the number of cycling periods to sustained violent preignition (SVPI), maximum engine noise requirements, total combustion chamber deposit weight, and average change in compression ratio. The data obtained in the foregoing tests are summarized in the tables below:

Table I 24-hour period to SVPI on tank fuel Example Example Unjnhib- V compo- IV compoited base sition sition gasoline Over-all average 4. 3 3. 3 2 Deviation from uninhibited base gasoline +2. 3 +1. 3

Table II Maximum noise requirements (Wiese) octane number Cadillac N 0.

E xample Example Unin- V eorn- IV oomhibited position position bass gasoline Over-all average 106 104. 5 117. 5 Deviation from uninhibited base gasoline 11.5 l3.0

Table 111 Total deposit weight, grams Cadillac No. E sample Example Unin corn- IV comhlblted position position, base gasoline Over-all average 6T. 6 72. 5 70. 7 Deviation from uninhibited base gasoline l2. 1 -7. 2

Table IV Average change in compression ratio Cadillac No. Example E xample Unin- V com- V cotnliibited position position base gasoline Over-ail average 0. 21 0. 35 0. 31 Deviation from uninhibited base gasoline -0. 10 +0. 04

The data in Table I clearly indicate that the addition agents of this invention effect a marked increase in the average time in which the engines can be operated before violent preignition occurs. Thus, where the engines were able to operate for only 48 hours without sustained violent preignition when using the uninhibited base fuel, the same engines were able to operate for an average of 103.2 and 79.2 hours without sustained violent preignition when using the respective gasoline compositions of Examples V and IV. The results set forth in Table II indicate that a reduction in engine octane requirements for noise-free operation is obtained with the use of the gasoline compositions of this invention. The data in Table III show that a substantial reduction in engine deposits is obtained by the use of gasoline compositions of this invention. The data in Table IV show either a reduction or a minimum increase in compression ratio for the gasoline compositions of this invention. The small increase in compression ratio obtained using the gasoline composition of Example IV as compared with the uninhibited base gasoline can be accounted for on the basis of the unusually low density of the deposits formed in engines Nos. 1, 2, and 4. In this connection, it can be noted that although an increase in the compression ratio was obtained in engines Nos. 1, 2, and 4 using the gasoline compositions of Example IV, the actual quantity of deposits was reduced as compared with those produced by the uninhabited base gasoline, see Table III.

Additional gasoline compositions according to this invention were made up by adding the addition agents prepared in accordance with Example I, II, and III to a base gasoline having the following typical inspections:

The tetraethyl lead in the foregoing gasoline was added in the form of a commercial aviation mix containing 1.9 cc. of ethylene dibromide and a dye. In addition, the foregoing base gasoline contained about 8.4 pounds per thousand barrels of the commercial oxidation inhibitor used in the Examples IV and V gasolines.

Example VI composition Example VII composition Example VIII com position Make-up Base gasoline, described above,

volume percent Addition agent of Ex. I:

eorv Lbs. per 1,000 bbls Addition agent of Ex. II Theory Lbs. per 1,000 bbls Addition agent of Ex. II

heory Lbs. per 1,000 hbls The foregoing compositions were subjected to the standard ASTM D381-50 test for gum. Very briefly, this test involves evaporation of a gasoline sample to dryness under a stream of preheated air at approximately 320 F. The gum is the amount of nonvolatile residue expressed as milligrams per 100 ml. per sample. The data obtained in these tests are summarized in the following table:

The data in the foregoing table clearly demonstrate that the addition agents of this invention can be added to gasoline compositions in substantial proportions without a corresponding significant increase in the gasoline gum content. This is an important advantage, since by way of comparison, it was found that the addition of only 82 pounds per 1000 barrels (0.175 theory) of tricresyl phosphate, a commercial preignition inhibitor, to the same base gasoline increased the gum content under the same test to 14 mg. per 100 ml.

The antistalling properties of the addition products described herein were demonstrated testing gasoline compositions prepared by incorporating various concentrations of the addition products of Examples I, II, and III in separate samples of an aviation grade gasoline that had a strong tendency to promote engine stalling. A typical sample of the base gasoline employed in these compositions had the following inspections:

Gravity, API 68.0 Specific gravity, 60/60 F 0.709 Knock rating:

Certain of the compositions prepared as described above also contained 0.5 percent by volume of an approximate 100 S.U.S./ 100 F. Texas lubricating distillate, a sample of which had the following inspections:

Gravity, API 24.5 Viscosity, SUV, sec.:

210 F. 38.3 Viscosity index 16 Pour, F. 60 Color, ASTM Union 2.0 Carbon residue, Conradson, percent 0.02

Neutralization value, ASTM D974-51T, Total acid number 0.05

The conditions at which the engine was operated are set forth below.

Cooling water temperature, F.:

In Out 5 Crankcase oil temperature, F. -150 Carburetor air intake temperature 39- 41 Relative humidity, percent 82- 85 The operating cycle of the engine included after temperatures became stabilized, operation for five minutes at 1500 rpm. at brake horsepower (B.H.P.) load. During this period the carburetor throttle plate becomes chilled and ice formations are allowed to build up After this five-minute run, the throttle was closed to the preset position to allow 450 rpm. idle speed. If the engine idled satisfactorily for 30 seconds, the fuel was considered nonstalling during that operating cycle.

The make-up of the test compositions and the results of the engine stalling tests are summarized in the following table:

Table Concentratlon, Engine Comactive test posi- Base fuel Additive ingrestalls per tion client, 5 operatprrccnt ing cycles y Weight Base gasoline, 180" 5 F. 50% ASTM distillation point. IX.. Base gasoline Example I addi- 0.01 0

tlon product. X llasu gasolini plus (lo .01 l

0.5 vol. percent o S. U.S./100 F. Texas oil. XI"... llasr' asoline plus do .04 0

0.5 01. percent. 100 S. I,S.,/l00 F. Texas oil. XIL", Base gasoline Example II nddi- .01 0

tion product. XIII, Base gasoline plus ,do .01 0

0.5 Vol. percent 100 S. US$100 F. Texasoil. XIV Bose gasoline plus (lo .04 0

0.5 Vol. percent 100 S. U.S./l00 F. 'lcxas oil. XV Bast gasoline Examplcllladdi .01 0

tion product. XYL Base gasoline plus .de .01 0

0.5 Vol. per ent 100 S. $100 F. Tcxc. il. XVII Base gflSUIlIlt plus de .04 0

0.5 Vol. per-rent 100 S. U.S./l00 F. Texas oil.

From the results presented in the foregoing table it is apparent that gasolines having a 50 percent ASTM distillation point such as to produce an engine stalling problem are markedly improved by incorporation therein of small amounts of the herein-disclosed addition products.

The gasoline compositions of this invention can also contain other conventional addition agents designed to improve one or more properties of the gasoline composition. For example, besides the addition agents of this invention, tetraethyl lead and ethylene dihalides, the gasoline compositions of this invention can contain antioxidants, metal deactivators, upper cylinder lubricants, dyes, supplemental antistalling agents, antirust agents, and the like.

While the herein-described invention has been defined in terms of certain specific addition agents and gasoline compositions, our invention is not limited thereto but includes other addition agents and other gasoline compositions within the scope of the foregoing description. Obviously, many modifications or variations of the invention as hereinabove set forth can be made without departing from the spirit and scope thereof. Accordingly, only such limitations should be imposed as are contained in the claims appended hereto.

This application is a division of our copending application Serial No. 569,684, filed March 6, 1956.

We claim:

1. A gasoline motor fuel comprising a major amount of a hydrocarbon mixture boiling in the gasoline range and containing about 0.003 to about 0.5 percent by weight of the composition of a substantially neutral addition product of an olefin oxide that contains 2 to 4 carbon atoms and a dialkyl acid o phosphate whose alkyl groups contain 5 to 8 carbon atoms.

2. A gasoline motor fuel comprising a major amount of a hydrocarbon mixture boiling in the gasoline range and containing tetraethyl lead in an amount normally tending to cause preignition of said fuel in the combustion chamber of a spark ignition, reciprocating internal combustion engine, and a minor amount, suflicient to inhibit such preignition, of a substantially neutral addition product of an olefin oxide that contains 2 to 4 carbon atoms and a dialkyl acid o-phosphate whose alltyl groups contain 5 to 8 carbon atoms.

3. A gasoline motor fuel comprising a major amount of a hydrocarbon mixture boiling in the gasoline range and containing ten-aethyl lead in an amount normally tending to cause preignition of said fuel in the combustion chamber of a spark ignition, reciprocating internal combustion engine, and a minor amount, sufficient to inhibit'such preignition, of a substantially neutral addition product of an olefin oxide that contains 2 to 4 carbon atoms and a dialkyl acid o-phosphate whose alkyl groups contain 5 to 8 carbon atoms, said minor amount being 0.15 to 1.5 times the theoretical amount required to convert the lead in the tetraethyl lead to lead orthophosphate, and at least 0.012 percent by weight of the composition.

4. The gasoline motor fuel composition of claim 3 wherein said minor amount is at least 0.2 to 0.4 times the theoretical amount required to convert the lead in the tetraethyl lead to lead orthophosphate.

5. A gasoline motor fuel comprising a major amount of a hydrocarbon mixture boiling in the gasoline range and containing tetraethyl lead in an amount normally tending to cause preignition of said fuel in the combustion chamber of a spark ignition, reciprocating internal combustion engine, and a minor amount, sufficient to inhibit such preignition, of a substantially neutral addition product of propylene oxide and di-(3-methylbutyl) acid o-phosphate, said minor amount being 0.15 to 1.5 times the theoretical amount required to convert the lead in the tetraethyl lead to lead orthophosphate, and at least 0.012 percent by weight of the composition.

6. A gasoline motor fuel comprising a major amount of a hydrocarbon mixture boiling in the gasoline range and containing tetraethyl lead in an amount normally tending to cause preignition of said fuel in the combustion chamber of a spark ignition, reciprocating internal combustion engine, and a minor amount, sufficient to inhibit such preignition, of a substantially neutral addition prodnot of propylene oxide and di-(Oxo-octyl) acid o-phosphate, said minor amount being 0.l5 to 1.5 times the theoretical amount required to convert the lead in the tetraethyl lead to lead orthophosphate, and at least 0.012 percent by weight of the composition.

7. A gasoline motor fuel comprising a major amount of a hydrocarbon mixture boiling in the gasoline range and containing tetraethyl lead in an amount normally tending to cause preignition of said fuel in the combustion chamber of a spark ignition, reciprocating internal combustion engine, and a minor amount, sufficient to inhibit such preignition, of a substantially neutral addition product of propylene oxide and 3-methylbutyl, 2-ethylhexyl acid o-phosphate, said minor amount being 0.15 to 1.5 times the theoretical amount required to convert the lead in the tetraethyl lead to lead orthophosphate, and at least 0.012 percent by weight of the composition.

8. A gasoline motor fuel comprising a major amount of a hydrocarbon mixture boiling in the gasoline range, tetraethyl lead in a proportion normally tending to cause preignition of said fuel in the combustion chamber of a spark ignition engine, said proportion being about 1.5 ml. to about 4.6 ml. per gallon of fuel, and about 0.15 to about 1 1.5 times the theoretical amount required to convert the lead in the tetraethyl lead to lead orthophosphate, of a substantially neutral addition product of (a) an olefin oxide that contains 2 to 4 carbon atoms, and (b) a dialkyl acid orthophosphate whose alkyl groups contain 5 to 8 carbon atoms.

9. A gasoline motor fuel comprising a major amount of a hydrocarbon mixture boiling in the gasoline range, tetraethyl lead in a proportion normally tending to cause preignition of said fuel in the combustion chamber of a spark ignition engine, said proportion being about 1.5 ml. to about 4.6 ml. per gallon of fuel, about 80 to 100 percent by volume, based on the volume of tetraethyl lead, of at least one ethylene dihalide selected from the group consisting of ethylene dibromide and ethylene dichloride, and about 0.2 to about 0.4 times the theoretical amount re quired to convert the lead in the tetraethyl lead to lead orthophosphate, of a substantially neutral addition product of (a) an olefin oxide that contains 2 to 4 carbon atoms, and (b) a dialkyl acid orthophosphate Whose alkyl groups contain 5 to 8 carbon atoms.

10. A gasoline motor fuel comprising a major amount of a hydrocarbon mixture boiling in the gasoline range that has a 50 percent ASTM distillation point not greater than about 235 F. and that normally tends to promote stalling of internal combustion engines, and containing an amount sufficient to inhibit the engine stalling tendencies of said hydrocarbon mixture of a substantially neutral addition product of an olefin oxide that contains 2 to 4 carbon atoms and a dialkyl acid o-phosphate whose alkyl groups contain 5 to 8 carbon atoms.

11. The composition of claim 10 wherein said minor amount is about 0.003 to about 0.01 percent by weight of the composition.

12. The composition of claim 10 wherein the hydrocarbon mixture contains additionally about 0.25 to about 0.75 percent by volume of the composition of a light lubricating oil having a viscosity at 100 F. of about to about 500 Saybolt Universal seconds.

13. The composition of claim 10 wherein said substantially neutral addition product is obtained from propylene oxide and 'di-(3-methylbutyl acid o-phosphate.

14. The composition of claim 10 wherein said substantially neutral addition product is obtained from propylene oxide and di-(Oxo-octyl) acid o-phosphate.

15. The composition of claim 10 wherein said substantially neutral addition product is obtained from propylene oxide and 3-methylbutyl,2-ethylhexyl acid o-phosphate.

References Cited in the file of this patent UNITED STATES PATENTS 2,405,560 Campbell Aug. 13, 1946 2,784,208 Ries Mar. 5, 1957 2,860,958 Gilbert Nov. 18, 1958 2,870,186 Orloff et a1. Jan. 20, 1959 2,892,691 Howell June 30, 1959 2,897,068 Pellegrini et a1 July 28, 1959 FOREIGN PATENTS 600,191 Great Britain Apr. 2, 1948 683,405 Great Britain Nov. 26, 1952 

10. A GASOLINE MOTOR FUEL COMPRISING A MAJOR AMOUNT OF A HYDROCARBON MIXTURE BOILING IN THE GASOLINE RANGE THAT HAS A 50 PERCENT ASTM DISTILLATTION POINT NOT GREATER THAN ABOUT 235*F. AND THAT NORMALLY TENDS TO PROMOTE STALLING OF INTERNAL COMBUSTION ENGINES, AND CONTAINING AN AMOUNT SUFFICIENT TO INHIBIT THE ENGINE STALLING TENDENCIES OF SAID HYDROCARBON MIXTURE OF A SUBSTANTIALLY NEUTRAL ADDITION PRODUCT OF AN OLEFIN OXIDE THAT CONTAINS 2 TO 4 CARBON ATOMS AND A DIALKYL ACID O-PHOSPHATE WHOSE ALKYL GROUP CONTAIN 5 TO 8 CARBON ATOMS.
 12. THE COMPOSITION OF CLAIM 10 WHEREIN THE HYDROCARBON MIXTURE CONTAINS ADDITIONALLY ABOUT 0.25 TO ABOUT 0.75 PERCENT BY VOLUME OF THE COMPOSITION OF A LIGHT LUBRICATING OIL HAVING A VISCOSITY OF 100*F. OF ABOUT 50 TO ABOUT 500 SAYBOLT UNIVERSAL SECONDS. 